Circuit breaker



May 25, 1954 J. A. DROBNEY ET AL 2,679,562

CIRCUIT BREAKER Filed Oct. 6, 1951 oFF oN Fg.|.

and Albert R. Cellerni.

Patented 'May 25, 1954 Joseph A. Drobney and Albert R. Cellerini,Bomen-Pa., assignors to Westinghouse Electric Corporation, EastPittsburgh, Pa.,

tion of Pennsylvania a corpora- Application ocmber 6, 1951, serial No.256,134

(ci. `o-ss) 14 Claims. l This invention relates to circuit breakers, andmore. particularly to circuit breakers for controlling lighting andmoderate power circuits.`

An object of the invention is to provide a circuit breaker having aswitch member biased open and an operating handle supporting the switchmember in closed position against its bias.

Another object of the invention isy to provide a circuit breaker havingan operating handle and a switch member'biased open and a support memyber on said switch member releasably engaging the handle.

A further object of the invention is to provide a circuitbreaker havingan operating handle, a switch member biased open, a supportmemberbetween the handle and the switch member and trip means for disengagingthe support member from said handle to effect opening of the breaker.

Another object of the invention is to provide a small compact circuitbreaker that is simple in construction, reliable inA operation and inexvpensive to manufacture.

The novel features that are considered characteristic of the inventionare set forth in particular in the appended claims.

withadditional objects and advantages thereof, will be bestunderstoodfrom the following detailed-description thereof when read inconjunctiony with the accompanying drawing.

yIn said drawing:

Figure 1 is a side elevationalview, partly in section and with the coverplate partly broken away, of a circuit breaker in the closed positionembodying the principles of the invention,

Fig. 2 is a view similar to Fig. 1 but showing the parts in the trippedopen position.

Referring to the drawing, the circuit breaker 'comprises a casing and acooperating cover plate I3, a fragment of which is shown in Fig.- 1broken away.r A stationary contact |'5` is mounted on a conductingstripV I'|` which extends through an opening in one endA wall of thecasing and has a terminal connecting screw I9 at its other end. Amovable switch member or arm 2| has :spaced side members 22 thereon(only one being shown) adjacent one end thereof throughwliich extendsapin 23. The ends of the pin 23 extend into companionslots 25 (only onebeing shown) vin the side wallof` the casing andin the cover plate I3.The switch arm 2| at its outer end ,carriesa movable'contact 21 forcooperating-with the stationary contact |5. The switch arm 2|v is biasedopen by means of a spring 29 compressed between a. spring seat 28 in thebasek of the cas- The invention itself, both as to construction andoperation, togetherk ing I I and a spring guide '30 on the switch arm2|. An operating handle 3| 'of moldedinsulating materialis pivotallymounted on a pin 33 supported in suitabler bearing openings (not shown)in the side wall of the 'casing I I and in the cover plate I3. AThehandle 3| extends outwardly through an openingA 31 in the casing I I'andA 'substantiallyy closes the opening in all positions of the handle.The `inner end of the handle 3| is provided with a projection '39 havingar slightly concave surface' 4| which, in the closed position of thebreaker,rk engages ther rounded upper end of a support member 43 theother end of which is pivotally connected by means of a pivot pin 45 tothe side members 22 of the switch arm 2|.

A relatively light spring 4l compressed between a spring seat 49-in thecasing l|I and the support memberv 43 biases'the support membercounterclockwise about the pivot 45 against a projection 5|y on thecasing II in whichlposition the point of contact 39-4I of the handle 3|and the support member 43 is substantially in line withr the f pivots 33and `45, respectively, of the handle and thek support member, thusholding the switch armk 2| in the closed contact position.

The contacts are opened manually by countery .clockwise movement of theoperating handle 3| from the Onposition to the Off position (indicatedby dot and dash lines, Fig. 1). During this movement of the handle 3|,the friction between the. projection 39 and the end of the support 43 isnot sufficient tocause rotation of the support member 43 against thebias of the spring 41. Consequently, the projection 39 isdisengaged fromthe support member 43 permitting the spring 29 to movethe switch arm 2|to the open position in which it appears in Fig. 2. During the manualopening movement, the support member 43 moves upwardly to the positionindicated by dot and dash lines at 43a (Fig. l). The opening movement ofthe switch arm2| is limited by engagement thereof'with a surface 53 onthe casingk and by engagement of the pin 23 with kthe upper ends of theslots 25.

The contacts'are closed manually by move-"- ment of the handle 3| fromthe Off (shown by dot and dash lines in Fig. l) to the On handle bringsthe concave surface 4I into engagement with the end of the supportmem-ber 43 which is then biased by the spring 41 to the position shownin Fig. '1 substantially in line with the pivots 33-65 or slightlyoverset to the left of a line drawn through the centers of the pivots33--45- It will be observed that the slots 25 are disposed at a slightangle to provide a wiping action between the contacts as they areclosed.

The circuit breaker is opened automatically in response to overloadcurrents by means of a thermally and magnetically responsive trip deviceindicated generally at 5l. The trip device comprises a binietal element59 having one end suitably secured, preferably by welding, to the innerend of a conducting strip 3i which extends out through an opening in theend wall of the casing ii and is provided at its other end with aconnecting screw S3. The connected ends of the bimetal element 59 andthe conducting strip 6l are seated in a notch inthe casing Il in orderto accurately position the trip device.

The bimetal element 59 from a point just below its point of connectionwith the strip 6I extends inwardly at an angle and the free end of thebimetal element 53 is connected by means of a flexible conductor S5 tothe left-hand end of the switch arm 2i. Disposed adjacent the free endof the bimetal element 59 is an ear 61 formed on a projection 63 on thesupport member 43.

Secured to the bimetal element in a suitable manner, for instance, bywelding is a resilient member or spring strip 'ii having a main bodyspaced from the bimetal element and extending substantially parallelthereto on the side of the bimetal away from the support member 43. Amagnetic member 'i3 is rigidly secured to the bimetal element 53 and acooperating magnetic member or armature l5 is mounted on the springstrip l. An adjusting screw 'i threadedly engaging the free end of thespring strip El and locked in place by a lock nut 1Q extends through aclearance opening in the bimetal element 53 and has its end disposedadjacent the ear Gl'.

'When an overload current occurs below a predetermined value of, forexample, 1000% of normal rated current, the bimetal element 59 becomesheated by the excessive current and when heated a predetermined amountdeilects toward the right (Fig. l) engaging the ear G'i and moving thesupport member 43 clockwise about its pivot 45 against the bias of thespring 41. During this movement, the handle 3 i, due to the frictionbetween the surface di and the end of the support member 23, rotatescounterclocliwise. This action continues until the support member 113escapes from the concave surface 4i whereupon the spring 29 acts to movethe switch arm 2| to the open position moving the support member to theposition in which it is shown in Fig. 2. After escaping from the surface4i, the upward movement of the support member 43 causes the upper endthereof to engage a projection 8| on the handle 3| and move the latterto an intermediate indicating pcsition shown in Fig. 2 in full lines.

The parts are shown in the tripped open position in Fig. 2. In thisposition, the spring 4l biases the support member 43 and the handletoward the Fig. l position, but since the spring 29 is stronger than thespring 4l, the parts will be held in the Fig. 2 position until thehandle 3i is moved to the Reset position shown in dot and dash lines inFig. 2. When the handle is moved to the Reset position, it frees thesupport member i3 which is immediately snapped countercloclrwise by thespring i1 to its position against the stop 5i. Thereafter the contactsare closed in the previously described manner by movement oi the handle3i clockwise to the On position. During this movement the cam surface iion the handle engages and cams the support member lli downwardly to movethe switch arm to the closed position.

Upon the occurrence of an overload current above 10C0% of normal ratedcurrent, or a short circuit current, the electromagnet 13 -15 isenergized sufiiciently to attract the armature 15 and bend the springstrip ii causing the screw 11 to engage and actua-te the support member43 to thereby eifect instantaneous opening of the contacts. Following aninstantaneous opening operation, the breaker mechanism is reset and thecontacts closed in the previously described manner by iirst moving thehandle 3l counterclockwise to the Reset position and then clockwise tothe On position.

The invention provides a circuit breaker of simple construction andhaving a minimum number of parts. The circuit breaker is trip free ofthe operating handle and is provided with a thermally andelectromagnetically responsive trip device, the electromagnetic tripbeing supported entirely on the thermal element.

While the invention has been disclosed in accordance with the provisionsof the patent statutes, it is to be understood that various changes inthe structural details and arrrangement of parts may be made withoutdeparting from some of the essential features of the invention.

We claim as our invention:

1. A circuit breaker comprising a movable switch member biased to openposition and movable to open and close the circuit, an operating handlemovable to an open position and to a closed position, a support memberon said movable switch member releasably engaging said handle tomaintain said switch member in the closed position, a spring biasingsaid support member to a normal position relative to said handle, manualmovement of said handle to said open position causing release of saidsupport member from said handle to permit opening movement of saidswitch member, and a trip device responsive to overload currents forengaging and releasing said support member from said handle to permitopening movement of said switch member.

2. A circuit breaker comprising a movable switch member movable to anopen position and to a closed position to open and close the circuit,biasing means biasing said switch member to open position, a pivotedoperating handle movable to an open position and to a closed position, asupport member mounted on said switch member and releasably engagingsaid handle to maintain said switch member in the closed position,spring means biasing said support member about its mounting on saidswitch member to a normal position against a fixed stop, said handlewhen moved to said open position causing release of' said support memberfrom said handle to permit said biasing means to move said switch memberto open position, and a trip device operable in response to overloadcurrents to engage and release said support member from said handle toeffect automatic opening of said switch member.

3. A circuit breaker comprising a movable switch member biased to openposition and movable to open and close the circuit, an operating handlemovable to an open position and to a closed position, a support memberdisposed between said handle and said movable switch member normallyreleasably restraining said switch member in closed position, saidsupport member being released from said handle upon movement of saidhandle to said open position to permit opening movement of said switchmember, and a trip device operable in response to abnormal circuitconditions to engage and move said support member to effect release ofsaid member from said handle to permit opening movement of said switchmember.

4. A circuit breaker comprising a movable switch member biased open andmovable to open and close the circuit, an operating handle movable to anopen position and to a closed position, a pivotal support memberdisposed between said handle and said movable switch member normallyreleasably restraining said movable switch member in closed position,movement of said handle to said open position effecting release of saidsupport member from said handle to permit opening movement of saidswitch member, and a bimetal element heated in response to overloadcurrents and operable when heated a predetermined amount to engage saidsupport member and eiiect release of said support member from saidhandle to permit opening movement of said switch member.

5. A circuit breaker comprisingr a switch member biased open and movableto open and close the circuit, an operating handle movable to an openposition and to a closed position, a support member disposed betweensaid handle and said switch member normally releasably restraining saidswitch member in closed position, movement of said handle to said openposition effecting release of said support member from said heated apredetermined amount to engage said support member and eiiect release ofsaid support member from said handle to permit opening movement of saidswitch member, and a projection on said handle engageable by saidsupport between said handle and said switch member normally releasablyrestraining said switch member in closed position, stop means limitingthe movement of said support member in one direction relative to saidhandle, spring means biasing member against said stop means, a

opening movement of said switch member.

7. A circuit breaker comprising a pivoted switch member biased open andmovable to open and close the circuit, an operating handle movable to anopen position and to a closed position to eilect manual opening andclosing movement of said switch member, a support member disposedbetween said handle and said pivoted switch member normally releasablyrestraining said switch member in closed position, stop means limi-tingthe movement of said support member in one direction relative to saidhandle, spring means biasing said support member against said stopmeans, a projection on said support member, a bimetal element having oneend supported and the other end free, and thermal bending of saidbimetal element causing the free end thereof to engage said projectionand effect release of said support member from said handle to permitopening movement of said switch member.

8. A circuit breaker comprising a movable switch member biased open andmovable to open and close the circuit, an operating handle movable to anopen position and to a closed position, a support member pivotallyconnected to said movable switch member and releasably engaging saidhandle to restrain said switch member in closed position, and a tripdevice operable in response to overload currents to engage and releasesaid support member from said handle and permit opening movement of saidswitch member.

9. A circuit breaker comprising a switch member biased open and movableto open and close the circuit, an operating handle movable to an openposition and to a closed position, a support member pivotally connectedto said switch member and releasably engaging said handle to restrainsaid' switch member in closed position, and a trip device operable inresponse to overload currents to engage and release said support memberfrom said handle to permit opening movement of said switch member, andsaid support member when released by said trip device engaging andmoving said handle to an intermediate indicating position.

10. A circuit breaker comprising a switch member biased to open positionand movable to open and close the circuit, an operating handle movableto an open position and to a closed position to effect manual openingand closing movement of said switch member, a support member having yoneend releasably engaging said handle and the other end pivotally engagingsaid switch member, a trip device comprising a bimetal element havingone end supported and the other end free, said bimetal element bendingwhen heated in response to overload currents below a predetermined valueto effect release of said one end of said support member from saidhandle and opening movement of said switch member, and electroresponsivemeans operable in response to overload currents above said predeterminedvalue to engage and eifect release of said one end of said supportmember and instantaneous opening movement of said switch member.

11. A circuit breaker comprising a switch member biased open and movableto open and close the circuit, an operating posi handle movable to anmember, a resilient member having one end supported adjacent thesupported end of said bimetal element, electroresponsive meanscomprising a magnetic member mounted on said bimetal element and anarmature mounted on said re silient member, and said electroresponsivemeans when energized in response to overload currents above saidpredetermined value bending said resilient member and causing saidresilient member to engage and release said support member from saidhandle to effect instantaneous opening movement of said switch member.

12. A circuit breaker comprising a switch member biased open and movableto open and close the circuit, an operating handle movable to an openand to a closed position to effect manual opening and closing movementof said switch member, a support member having one end releasablyengaging said switch member, said support member having a projectionthereon, a trip device comprising a bimetal element having one yendsupported and the other end free, said bimetal element bending inresponse to overload currents below a predetermined value to engage saidprojection and release said support member from said handle to permitopening movement of said switch member, a resilient member having oneend supported adjacent the supported end of said bimetal element and theother end free, an adjusting screw on the free end of said resilientmember, electromagnetic means comprising a rst magnetic member on saidbimetal element and a second magnetic member on said resilient member,said electromagnetic means when energized by overload currents abovesaid predetermined value bending said resilient member and causing saidadjusting screw to engage said projection and instantaneously releasesaid support member from said handle.

13. A circuit breaker comprising a switch member biased open and movableto open and close the circuit, an operating handle movable to an openand to a closed position to effect manual opening and closing movementof said switch member, a support member having one end releasablyengaging said switch member, said support member having a projectionthereon, a trip device comprising a bimetal element having one endsupported and the other end free, said blmetal element bending inresponse to overload currents below a predetermined value to engage saidprojection and release said support member from said handle to permitopening movement of said switch member, a resilient member having oneend supported adjacent the supported end of said bimetal element and theother end free, an adjusting screw on the free end of said resilientmember, electromagnetic means comprising a. first magnetic member onsaid bimetal element and a second magnetic member on said resilientmember, said electromagnetic means when energized by overload currentsabove said predetermined value bending said resilient member and causingsaid adjusting screw to engage said projection and instantaneouslyrelease said support member from said handle, and said adjusting screwbeing adjustable to vari,T the magnetic tripping point of the breakerwhile the thermal tripping point remains constant.

le. A circuit breaker comprising a switch member biased open and movableto open and close the circuit, an operating handle having a plurality ofprojections thereon and movable to effeet opening and closing movementsof said switch member, a support member having one end releasablysupported on one of said projections and the other end pivotallysupported on said switch member, a trip device operable in response tooverload currents to engage and release said one end of said supportmember from said one projection to permit longitudinal movement or saidsupport member and opening movement of said switch member, andlongitudinal movement of said support member causing said one endthereof to engage another of said projections and actuate said handle toan indicating position.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,360,684 Jennings Oct. 17, 1944 2,443,090 Wise June 8, 19482,534,938 Woodward Dec. 19, 1950 2,568,423 Walker et al Sept. 18, 19512,573,306 Casey Oct. 30, 1951

